I can only think of 2 fringe recovery/Live CDs that don't have it on ones that are current.

TomRB and Damn Small.

Most (if not all others I have tried and seen) now by default have xfs in the initrd, or compiled in directly

But, since grub dunnah like xfs (really it is only the XFS_Freeze that has to happen when writing the grub files, that causes errors regularly), I am using EXT2 for /boot since I automount it read-only at boot it doesn't need anything. Only time I make it read-write is for kernel and grub updates.

Beyond that, its not a big deal.